Method for hydraulic fracture dimensions determination

Abstract

A numerical model of a polymer-based fracturing fluid displacement from a fracture and a filtrate zone by a formation fluid is provided for calculating a change of a fracturing fluid concentration in a produced fluid and for calculating a change of a polymer concentration in the recovered fracturing fluid. Throughout the entire fracturing fluid recovery the produced fluid samples are periodically taken from a well mouth. The fracturing fluid concentration and the polymer concentration in the samples are measured. The measurement results are compared with the model calculations and the fracture length and width are determined based on a match of the measurement results and the model calculations.

1. A method for determining hydraulic fracture dimensions comprising:
 creating a fracture in a borehole zone by injecting a polymer-based fracturing fluid into a wellbore so that a fracturing fluid filtrate penetrates into a formation around the fracture through a fracture surface and creates a filtrate zone around the fracture, 
 providing a numerical model for displacement of the fracturing fluid from the fracture and the filtrate zone, by a formation fluid, the model being made based upon given formation parameters, fracturing data, and predicted fracture dimensions, 
 using the model for calculating a change of a recovered fracturing fluid concentration in a produced fluid during production as a function of time and for calculating a change of a polymer concentration in the recovered fracturing fluid as a function of time, 
 putting the well into production, 
 periodically taking fluid samples from a well mouth during a fracturing fluid recovery, 
 measuring recovered fracturing fluid concentration and polymer concentration in the samples, 
 comparing the measurement results with the model calculations; and 
 determining fracture length and width on the basis of a match of the measurement results and the model calculations, the match being obtained by correcting the fracture length and width so as to provide a constant total fracture volume. 
 
     
     
       2. The method of  claim 1  wherein the fracturing fluid contains a tracer to differentiate the fracturing fluid from a formation water. 
     
     
       3. The method of  claim 1  wherein the polymer in the polymer-based fracturing fluid is guar.